The invention relates to an arrangement for the automatic draining of water quantities collected in a container which are precipitated, for example, in a filter arrangement for fuel systems from the fuel for internal-combustion engines.
An arrangement of this type is known, for example, from the German Patent Document DE-OS 32 17 162. The water separated by a fuel filter, because of the force of gravity, collects in the lower part of a container comprising the filter element. When the water reaches a given level, a shut-off device is opened up either mechanically by a float or electromagnetically by the signals of a sensor sensing the height of the water level, by means of which shut-off device the water is sucked off while utilizing the vacuum existing in the intake pipe of the internal-combustion engine. However, it is also suggested to use a separate pump. This pump can then be connected at the same time as the shut-off device is actuated to open. A time function element may also be connected into the electric circuit which holds the shut-off arrangement open for a given time for the discharge of a defined amount of water. It is a disadvantage of this arrangement that the vacuum in the intake pipe is not always sufficient for actually sucking the water off to the desired extent, and the use of a separate pumping arrangement is expensive. In the German Patent Document DE-OS 32 17 162, the use of a pumping arrangement is therefore suggested which operates according to the Venturi principle and which is arranged in the air intake pipe of the internal-combustion engine. This suggested installation is hardly less expensive than a separate pump and, in addition, represents an undesirable flow obstacle in the air intake pipe.
Another arrangement of this type is known from the German Patent Document DE-PS 37 40 804. Here, it is suggested to arrange a Venturi nozzle in the return flow pipe of the fuel pump for the sucking-off of the water, the suction connection of this Venturi nozzle being connected with an immersion pipe which dips into the collected water.
It is an object of the invention to provide a safe and particularly simple arrangement for generating the required pressure difference for the pumping-out of the water.
In order to achieve this object, the invention provides, in an arrangement of the initially described type, a piston which can be displaced in the container of the water separator and the one side of which is acted upon by the pressure of a pressure medium, preferably by the fuel which is pressurized by the fuel pump, and the other side of which borders on the water reservoir containing water to be removed. When the piston is acted upon by pressure, connections to other spaces of the container are preferably closed automatically by a non-return valve and the outlet valve is opened automatically.
In one preferred embodiment of the invention, the water collects on the top side of the piston. The piston moves upward for the draining of the water.
In another preferred embodiment of the invention, the piston has a closable passage. Here, the water collects on the bottom side of the piston. The piston is moved downward for the draining of the water.
These constructions have the advantage that an already existing assembly is used for making available the working medium, specifically preferably the fuel pump and the fuel which is pressurized by the fuel pump. The required components, specifically the piston, connecting lines and valves are relatively simple and inexpensive, and, in particular, a sufficient amount of pressure medium is always available with a sufficient pressure level irrespective of the operating condition of the internal-combustion engine.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.